The application and use of dataforms, including common forms of bar codes, are extensive and growing. For present purposes, "dataform" is defined as including all arrangements whereby data is fixed in some form of machine readable copy. Typically dataforms comprise patterns of elements of differing reflectivity (black and white, for example) which can be printed on labels and other items. Basic aspects of encoding, reading or data extraction and decoding of dataforms are well known.
A MaxiCode is a form of two-dimensional dataform which includes a bull's eye target in the center of the dataform and a fixed number of hexagonal data cells surrounding the bull's eye pattern. A MaxiCode is shown in FIG. 1. A binary encoding protocol is utilized to represent encoded data by arrangements of black and white data cells. FIG. 2 is a diagrammatic map of the data cells of a MaxiCode. As shown, there are included 18 orientation cells marked "B" or "W" surrounding the bull's eye (which would be in the center). Of these orientation cells, those marked B are always black or of low reflectivity and those marked W are always white or of higher reflectivity. The known markings of these orientation cells enables determination of which of the four outer edges is the top edge of a MaxiCode. The remaining data cells can be black or white as determined by the data to be stored in a particular MaxiCode.
A dataform reader, whether using laser or image based technology, is typically programmed to implement a particular reading protocol designed for use with a specific form of dataform, such as a MaxiCode. Decoding normally includes two basic steps. The first is data extraction which includes processing image data to determine the black or white reflectivity characteristic of each dataform cell.
The second step is decoding based on the binary black or white value of each data cell. For example, a MaxiCode label as illustrated includes 866 hexagonal data cells each having a binary 1 (black) or 0 (white) value. Data extraction includes processing image data representative of illumination reflected from a MaxiCode positioned in a target area in order to generate 866 bits of binary data. Decoding includes processing the binary data to recover the data file originally encoded in compressed or other form into the binary values of the data cells of the MaxiCode.